TABLE OF CONTENTS
- Definition of SAD
- Cause of SAD
- Associated diagnosis
What is Seasonal Affective Disorder (SAD)?
Seasonal affective disorder (SAD), also known as winter depression or winter blues, is a subtype of mood disorder consisting of recurrent major depressive episodes of varying severity, which occur with a seasonal pattern. The most common type of SAD is winter depression with symptoms beginning in autumn and winter. This is followed by full remission or hypomanic states (mild state of mania) during the following spring and summer. A rare form of SAD occurs during the summer. SAD is generally characterised by four central features;
1. Recurrent major depressive episodes, which start around the same time each year, for example September to October, and end around the same time each year, for example March to April,
2. Full remission of symptoms during the unaffected period of the year, for example May to August,
3. Relatively more seasonal depressive episodes than non-seasonal episodes, over the lifetime course of the illness,
4. Seasonal depressive episodes occur in at least 2 consecutive years.
Subsyndromal SAD is a disorder with similar but milder symptoms to SAD, which do not affect the patient's ability to function. It has been reported that there is a paucity of information concerning the incidence and detection of SAD in UK populations. Prevalence rates suggested by studies carried out have ranged from 1 to 12% depending on the diagnostic criteria used. The overall lifetime incidence of SAD is said to range from 0 to 9.7%, depending on the specific population studied and how it is diagnosed. SAD prevalence may be higher in northern latitudes than southern latitudes and may vary within ethnic groups at the same latitude. It has been reported that the risk of SAD probably increases if people move to live further away from the equator. Almost all the studies of the incidence of SAD report that women are more likely to suffer from SAD. The average ratio of women to men across all studies is 1.8 to 1.2 During the reproductive years, female sufferers predominate; however a reduction in incidence and a narrowing of gender differences is seen in old age.
With respect to age, studies report that the life time incidence of SAD increases with age until around age 60. After the age of 50-54, it is reported that the incidence declines dramatically and as such, over the age of 65 the incidence of SAD is very low. Regardless of this however, patients over 65 may still present to hospitals for treatment. It has been suggested that the response of patients over 65 to treatment does not differ from that of younger patients with SAD. It should be noted that the low incidence of SAD in older individuals may be as a result of misdiagnosis as physicians may consider symptoms presented by such individuals as being down to old age and not SAD. Children also suffer from SAD, although this is quite rare as children have more opportunity than adults to play and interact outdoors thereby exposing them to more sunlight and as such suppressing any possible triggers of SAD; however, incidence rates rise at puberty. Severity of SAD can be mild, moderate or severe.
Cause of SAD
The cause of SAD is unknown. However it is thought that in people predisposed to winter SAD, decreasing daylight period as winter approaches is thought to be a trigger. Essentially, the onset of SAD is thought to be associated with seasonal reduction in daylight, and its remission to ensuing seasonal increase in daylight.
Symptoms of SAD include,
1. Hypersomnia (excessive sleeping)
2. Chocolate/carbohydrate craving
3. Impaired concentration
5. Weight gain
6. Low libido
7. Anhedonia (lack of pleasure or of the capacity to experience it)
8. Low mood, which is often worse in the morning
9. Loss of interest
10. Poor motivation
12. Anergia (lack of energy)
13. Social withdrawal
14. In children, symptoms may also include grades falling in the winter and rising in the spring, or poor relations at school during winter
Patients with winter SAD may experience a reversal of their winter symptoms during the summer, that is, elevated mood, increased libido, social activity and energy, decreased sleep requirements, appetite and mild hypomania (mild state of mania).
Several conditions have been reported to be associated with SAD as they share similar mechanisms. These include,
1. Panic disorders
2. Social phobia
3. Bulimia nervosa
4. Chronic fatigue syndrome
5. Premenstrual syndrome
6. May also be associated with attention-deficit/hyperactivity disorder (ADHD)
7. A pattern of seasonal alcohol use may also be associated with SAD
Treatment options for SAD include,
1. Regular exposure to natural light outdoors (natural light therapy) as much as possible in autumn and winter, particularly in the morning. This is advisable for milder symptoms and in conjunction with other therapies in severe cases.
2. Continuing regular exercise. This is antidepressant in itself and helps to reduce weight gain and promote a feeling of mastery. Exercising outdoors (walking or light jogging) is even more beneficial through concurrent light exposure. This should also be used in conjunction with other therapies.
3. Light therapy which has been recommended as the first line treatment for SAD. This includes the use of light boxes. Alternatives include light sources adapted for the workplace (such as desk lights or fitments above computer screens), rechargeable light visors and dawn-simulating alarm clocks (body clocks). Both subsyndromal and full-syndromal SAD may respond to light therapy.
4. Cognitive behavioural therapy. This has some effectiveness in improving dysfunctional automatic thoughts and attitudes, behaviour withdrawal and low rates of positive reinforcements. When used in combination with light therapy, cognitive behavioural therapy has been found to be effective in the treatment and prevention against recurrence of SAD.
5. Pharmacotherapy (antidepressants such as Fluoxetine and Sertraline). These are often used in moderate to severe cases, either alone or in conjunction with light therapy.